High-Gain Circularly Polarized Lens Antenna for Terahertz Applications

A high-gain circularly polarized (CP) lens antenna fed by a standard linearly polarized (LP) pyramidal horn operating at 300 GHz is proposed in this letter. The high-gain CP lens consists of discrete variable-height dielectric posts and grating. The height of each dielectric post is tuned to realize the required transmission phase, forming a planar wavefront above the lens aperture. By integrating the bottom dielectric grating with anisotropic characteristic, the dielectric lens can transform the incident LP waves from the feed source into CP radiation waves. Three-dimensional (3-D) printing technique is utilized to fabricate the terahertz (THz) CP lens for simplifying the fabrication process and reducing the cost. Measured results show that the designed lens can realize right-hand circular polarization radiation with a gain of 30.8 dBic at 300 GHz. The measured 1 dB gain bandwidth and 3 dB axial-ratio bandwidth of the THz CP lens can reach 13.3% and 18.8%, respectively. 3-D printed dielectric CP lens for use at THz frequencies is demonstrated, opening new possibilities for future high-speed wireless communications.